Arrangement for supplying heated air to furnaces



N 11, A924. LSMJEE w. H. OWEN ARRANGEMENT FOR SUPPLYING HEATED AIR TO FURNACES Filed May 1922 F i. Fig. 2.

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" RANGEMENT FOR SUPPLYING HEATED AIR T0 runiracm.

Application filled March 15, 1922. Serial Kc 544,043..

To all whom it may concern:

Be it known that 1, WILLIAM HENRY OWEN, residing at 19, Home Park Road, vVimbledon, S. W. 19, in the county of London, England, have invented certain new and useful Improvements in or Relating to Arrangements for Eiupplying Heated Air to Furnaces,

fication.

This invention relates to preheatingair for furnaces, and has reference more par of which the following is a speciticularly to the system in which the air de livered to the furnaces above the grate is heated to a higher temperature than the air delivered to the ash-pit, that is toosay below the grate.

The main object of the invention is to facilitate the application of such a system to cylindrical marine or Scotch boilers, by the employment of air heaters situated immediately above the smoke boxes and in the path of the waste gases to the chimney, such heaters ellecting the heating of the air to the furnaces in two (or more) stages.

According to the invention the heat from the boiler or from the smoke boxes is utilized to maintain or increase the temperature of the hotter partof the air, viz that which is delivered above the rate to promote the combustion of therfue gases.

In order that such. hot air for the furnace shall have its temperature maintained as high as possible after leaving the heaters it is led according to the invention through ducts or passages arranged close to or upon the front end wall of the boiler and situated between or at the side of the openings of the ends of theiboiler tubes so that the said passages are also subject to the heat of the waste gases, being as it were jacketed with waste gas on one onboth sides.

These ducts or pa'ssages may conveniently be formed by the walls of the smoke bones and the boiler front, and be arranged to form supplementary heaters, not only main taining hut raising still further the temperature of the air.

The main heater above the smoke-box may adnantageouslyhe placed a little away from the boiler front, the interveningspace form= ing or accommodating a distributing helt or passages along the back of the main heater to distribute the hotter air to the passages leading to the furnaces. The cooler air may conveniently pass from the main heater to the ash-pits y passages arranged outside the wing smoke-boxes and be separated from the ducts for the hotter-air (it also in that position) by insulation or insulating walls. The whole arrangement may be enclosed in a casing with the ducts or passages for the hotter airnearest the boiler front, suitable valves or dampers being provided for controlling the supply to the furnaces and ash- .pits as desired.

In order that the invention may be clearly understood and readily carried into eifect referencewill now be had by way. of example to the accompanying diagrammatic drawings or sketches in which Fig. 1 is a front view, half in section, of a boilerv with the invention applied thereto and provided with super heaters for the steam. Three furnaces are shown for the purpose of illustration, but the invention may be applied to boilers having any number of furnaces. Fig. 2 is a side view thereof, partly in vertical central section,

Fig. 3 is a similar view to Fig, 2, hut with the vertical section running through the left-hand furnace and its smoke-box.

Figs. 4 and 5-are views corresponding to Figs. 1 and 2 but illustrating a boiler without steam super-heaters.

Referring more particularly to Figs. 1 to 3, of these dtawingsza represents the shell of the holler which is of the ordinar cylindrical marine or Scotch type ttlKllS provided'with smoketubes 0 and with three furnaces, F2, ("9 and c, 0 0 represents the smolrehoaesof these furnaces. interposed between these smoke-bores and the base or uptake cl leadin to the. funnel or chimney, is a chamber or con e which forms a two-stage heater for the air-supply to the furnace. This heater is provided with vertical smoke tubes f for the waste gases, the ends of these tubes being lined in the sheet metal floor and. root of the Mil chamloer 6, About one-third on: the way up,

the latter is divided horizontally into an upper and lower compartment by a horizontal partition or division plate g.

The air to be heated is admitted through an opening '5 in the upper middle front part of the chamher and flows outward ahove the division plate and undergoes the first stage of its heating as it makes its way through the nest of tubes. f, which may be staggered or be provided with battles to cause it to follovyi a zig-zag pathand promote the heate ect.

in lt then splits up, part going down the ducts or passages 7 outside the wing smoke boxes c to the ash-pits ofthe respective furnaces b 12 and through branch passages leading into the ash-pit of the central furnace from each side. This part of the air forms what is herein termed the cooler portion of the hot-air su ply. v

The other part of t e air inthe two-stage heater 6 turns back under the division plate g, and as it, travels again in and out between the smoke tubes f it undergoes the second heating stage and formsthe hotter or superheater part of thezair supply, which is de= livered to the furnaces above the grate bars. In order that this hotter air'shall have its temperature maintained as high as possible after leavingthe heater, "it is led out at the back of the heater c through one or 'b more openings is, as may be" convenient to the distributing belt or passage k 'and thence to the vertical ducts or down how passages 70 close to or upon the front end of the boiler and situated between (or at the side of) the ends of the group of boiler tubes a etc.

These duets or passages may conveniently be formed by the walls or partoithe walls of the smoke boxes or be structurally incorporated therewith, and being in direct con tact with the waste gases immediately leaving the boiler, they form supplementary heaters which not only maintain but actually raise still further the temperature of the downfiowing air.

The superheated air then passes to the tops of the mouths of the furnaces by dis-v tributing ducts is under the smoke-boxes, close to the boiler front plate and through suitable dampers we worked by lever handles Z.

In the arrangement illustrated, steam superheaiters are as stated fitted to the boilers, their headers n being fixed in the smokeboxes, and it will be seen that the air-ducts or passages 10 above referred to are placed behind the headers, and next to the boiler front.

Alternatively howeverthey may be near to the internal front of smoke-box and structurally incorporated therewith, or be partly in front of the headers andpartiy behind the same as may be found convenient according to circumstances, and air being delivered to the passages k below the smoke-box leading to the furnace through air-valves or dampers m, as before. a

The cooler, air would still pass from the main heater to the ash-pitstas explained by passages j 3 leading down and around the the inner sides of the wing ash-pits, by passages leading under the smoke-boxes and overhanging above the furnace fronts- -see Figs. 2 and 3. To the outer sides of the wing ashpits it is distributed simply by a prolongation of the passages 7' outside the wing smoke-boxes The whole arrangement is enclosed in a sheet metal casing, all the ducts for the hotter air being preferably next to the boiler front.

The various air-valves or dampers m are arranged as required in any convenient positions'and operated by handles or cranks Z.

In the arrangement shown in Figs. 4 and 5' the superheaters n are omitted and the whole depth of the s ace between the smoke boxes is utilized to orm the heating space or down-flow passage which is indicated 10 Suitable bailles p are provided to distribute the air through the tubes 7 before entering the passages especially when no distributing belt at the back or frontis provided. Baflles 13 may also be fitted as indicated in Fig. 5, in the downilow passages 70 in order to give the air a zig-zag path and so promote the transfer of heat ObVio'usly the above arrangements may be modified in various ways in carrying the invention into practice. For instance each smoke box might have a separate and independent air heater if desired, Also the numher and arrangement of passages, ducts and bafiles for the distribution of the air may be added to or modified according to the number of furnaces in the boiler, as convenient.

I claim- 1. In an air-heating arrangement for furnaces, the combination of means for heating all the air for combustion by waste gas, means for further heating a part of said air to a higher temperature by waste gas, means for supplying such hotter air to the space above the grate, and means for delivering the rest of said air below the grate, substantially as described.

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2. in an air-heating arrangement for tur- 3. ln an air-heating arrangement for for 1 relapse naoes the combination of a two-stage airheater comprisin two sections one above the other, verticaftubes for the waste gases extending through both sections, means for conducting all the air for combustion through the upper section, meansfor further heating a section, means or conducting the air from the lower section to the space above the grate, and means for conducting the rest of the air from the upper and cooler section to the space below the grate, substantially as described. v

4:.ln an v air-heating arrangement, theart of said air in the lower ;conducting part of such air along the side walls of the boiler to the space below the grate, and means for further heating the rest of such air in the second section and between the smoke boxes, and means for conducting such hotter air to the space above the grate, substantially as described. I

In testimony whereof I affix my'signature.

WILLIAM HENRY OWEN. 

